Fade in custom made beaver themer header

Hey folks, is there an easy way to display / fade in a custom created beaver themer header after scrolling the page for 300px? I could not use the beaver builder menu in the customizer so i had to use custom beaver themer menu.

Big header
Sticky small header

I’d like the “small header” to fade in on the home page after scrolling for about 300px.

Hey tribe, i found a piece of javascript and used it along with a beaver themer part.
It works only on scroll up on the home page.
CodePen JS
This solution works for me, althought i have only tested it in Firefox so far.
The problem i see - now i have two identical navigation bars - is this a problem for seo?